Conventionally, it has been already realized to manage an electricity rate and to perform an energy saving control by controlling an amount of used power and maximum power in a power load based on a target value set by a user. There is proposed “an electricity rate management apparatus having a means for setting a target value of an amount of power used by a power load in a predetermined period, a means for accumulating the value of an amount of power used by the power load in a unit time obtained by minutely dividing the predetermined period, a means for calculating a target value of the amount of power used in each unit time based on the target value of the amount of power used in the predetermined period and the amount of power used in each unit time, and a means for controlling the amount of power used by the power load based on the target value of the calculated amount of power used in each unit time” (refer to, for example, Patent Document 1) as a technology having an object of providing, for example, “an electricity rate management apparatus which can manage an electricity rate by setting a target value to an electricity rate, to an amount of power used by all the power loads or to CO2 in a facility in a predetermined period such as a unit of one month or one year and controlling an amount of used power and maximum power in the electric loads based on the target”.    Patent Document 1 Japanese Patent Application Laid-Open Publication No. 2001-327076 ([0006], [0009], FIG. 1.